Publications

Seram Island is located offshore West Papua, Eastern Indonesia. This tectonically complicated area is host of several oil fields such as Oseil and Bula. These oil fields lie on the Seram Fold-Thrust Belt (SFTB) which extends southeastward along the Banda Arc. Oil occurrences in this island are controlled by their position within tectonics related to the SFTB evolution. However, the SFTB extension to the offshore area is considered unattractive in terms of hydrocarbon potential compared to the island. This study focuses on petroleum system investigation in the offshore area, including the presence and the position of the source rock relative to the SFTB deformation. Retro-deformable palinspastic restoration was used to reconstruct the source rock history, combined with geochemical analyses and basin modeling. The geological features recognized on NE-SW seismic are foreland basin features. The source rock analysis showed the Jurassic interval is the primary source rock of the area (Adlan et al., 2016, Bradshaw et al., 1994, Price et al., 1987). The result showed that the Jurassic source rock reached oil maturation window in 33 Ma. Compressional tectonic event in late Neogene caused emergence of the imbrication block sequentially from west to east. This imbricated block emergence increased burial of the source rock in front of it basinward, thus the source rock in the frontal area reached the 1.3–2% Ro gas window before start of imbrication. Gas migration most likely displaced the existing oil from traps in the imbrication block. As a result source rock gradually changing in SFTB, onshore Seram Island is more oil prolific than the offshore area.